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For the KLM "Animal Hotel" for pets transported in the cargo hold by Air France/KLM, then no, that area is part of the airline's cargo facility and does not appear to be open to the public.
Even if the airline was able to grant you a special exception, accessing the facility would require leaving the secure area of the terminal, which would require passing through immigration, which may require a visa depending on your citizenship and circumstances.
If you do get a visa or are able to pass immigration in the Schengen Area visa-free, one thing you could consider is contacting the airline and ask about their policy about "short-checking" pets. There's a minimum layover time for airlines to do this, and six hours may not be long enough under their rules. But if you are able to short check the dog, it wouldn't go to the "animal hotel" at all; you'd go through immigration in Amsterdam and pick the pet up at baggage claim, then re-check the kennel at the check-in counter. Again, the airline may very well not permit this for a six hour layover, and it would increase the risk of things going wrong if your inbound flight is significantly delayed, but you could ask the airline. But this route requires passing immigration, so it may be a non-starter.